Near-field investigation of plasmonic silver nanowires in the mid infrared frequency range

We study experimentally the plasmon resonances of silver nanowires (length between 1.5-3 $\mu$m) in the mid infrared (IR) (9-11 $\mu$m) using scattering-type scanning near-field optical microscopy (s-SNOM). We identify the mid IR plasmon modes of Ag rods at different polarizations of the excitation laser via near-field phase and amplitude. By varying the wavelength of the incident laser the interaction between closely spaced nanowires is investigated.